The invention relates to improvements in cross cutters for running webs of paper, cardboard, metallic foil, plastic foil or the like, and more particularly to improvements in rotary knife holders or knife carriers which are utilized in such apparatus.
It is known to provide the rotary knife carriers of cross cutters for running webs of paper or the like with longitudinally extending peripheral recesses for elongated knives. Successive knives on one of the carriers (at one side of the path for the running web) cooperate with successive knives on the other carrier (at the other side of the path for the running web), not unlike the blades of shears or scissors, to sever the moving web in such a way that the cut is started at one marginal portion and proceeds transversely of and toward the other marginal portion of the running web. The selected planes of the knives in the respective recesses are or can be such that the cutting edges of the knives project from the respective recesses and that the knives are parallel or nearly parallel to imaginary tangents to the peripheral surfaces of the respective (normally cylindrical) carriers.
It is also known to employ readily detachable knives which are clamped against the respective carriers, namely against portions of surfaces bounding the respective recesses in the rotary drum-shaped carriers, and it is equally known to adjustably secure at least some knives to their carriers so that the knives on one of the carriers can be properly positioned relative to the complementary knives on the other carrier and/or that the knives can be adjusted in order to compensate for wear at and to sharpen the cutting edges. Reference may be had, for example, to German Petty Patent (Utility Model) No. 295 12 032.
The making of transverse cuts which begin at one marginal portion and proceed toward the other marginal portion of the running web is achieved by employing knives having a slightly helical shape. An important prerequisite for the making of clean cuts is that the pairs of cooperating knives on the two rotary carriers be properly adjusted relative to each other so that their cutting edges slide, without play, relative to each other in a manner known from the blades of shears, scissors or analogous cutting implements.